[Bug]: uri template auto resolve problem for optional path param

### Describe the bug

the auto resolved uri template for optional path param will have a redundant `/`.


### Reproduction

[playground](https://cadlplayground.z22.web.core.windows.net/cadl-azure/?c=aW1wb3J0ICJAdHlwZXNwZWMvaHR0cCI7DQp1c2luZyBIdHRwOw0KDQpAc2VydmljZQ0KbmFtZXNwYWNlIFRlc3TGHXJvdXRlKCIvb3B0aW9uYWwiKQ0Kb3AgdGVzdChAcGF0aCDENjogc3RyaW5nKTogdm9pZDs%3D&e=%40azure-tools%2Ftypespec-client-generator-core&options=%7B%7D)

### Checklist

- [x] Follow our [Code of Conduct](https://github.com/microsoft/typespec/blob/main/CODE_OF_CONDUCT.md)
- [x] Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
- [x] Check that this is a concrete bug. For Q&A open a [GitHub Discussion](https://github.com/Microsoft/typespec/discussions).
- [x] The provided reproduction is a [minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example) of the bug.